AFB or PMS – Beekeeping Diseases

Parasitic Mite Syndrome (PMS) is the destructive combination of mites, viruses, and general malaise that can overcome a colony with a high mite load.  At first glance some of the symptoms of PMS can look a lot like foulbrood disease.  I ran into this last week.

The hive in question started last spring as a 5 lb. package with Italian queen on drawn comb.  This instant colony filled out two brood chambers and produced two and a half supers of honey last year.  I felt that the mite load was acceptable all through the summer because I only saw a few mites on the screened bottom drop boards.  As the weather cooled the mite drops increased a bit.   I placed a formic acid pad on the colony in November and more mites came down, and I kept seeing heavy drops all through the fall.

Around this time I noticed lots of dying bees in front of the hive.  Concerned about Nosema, I checked with the microscope but found no spores.  The deaths tapered off – winter came – and now I find only about 3 frames of bees left with a small brood nest.

I observed several bees with deformed wings – signs of virus problems associated with Varroa.  When I pulled a frame, the first thing I noticed were the perforated cappings on the brood cells.  The thought of AFB immediately came to my mind.  I tested for “rope-like” consistency of the dead larvae with a twig.  Maybe – maybe not — What else could it be?  I put a quart of sugar syrup with Terramycin on the hive and closed them up – dismayed with the prospect of burning yet another colony.

Today, armed with camera, toothpicks, and sample jar I took another look and collected a couple of samples for microscopic examination.  If it is active  American Foulbrood, there will be plenty of spores to see.

Last year I had to deal with AFB and took a few pictures of the spores through the microscope.  The spores are small and numerous, and bounce around a lot because of Brownian motion.  The picture above is what you don’t want to find!

Today the larvae that I probed did not rope much at all, so I’m quite convinced that I jumped the gun with the AFB fears.  The microscope confirmed that no spores were present.  (Sometimes its hard to know you are looking at in a “normal” sample.  Digested pollen grains usually dominate bee gut microscopic images.  Pollen comes in lots of shapes, so don’t expect all gut samples to look alike, even with normal healthy bees.)

So,although I found no foulbrood, I still have a very weak distressed colony that may not make it until spring.  Now its time to reflect about what I should have done differently.  Varroa mites and the trouble they cause are not going away any time soon.

I did run across a good reference on this subject  which I’ll pass along:  IPM_American_Foulbrood_and_Varroa_Mites_by_Simone.pdf


  1. Interesting blog. I read all the posts. I’ll keep the link for when I’m struggling with my own garden. We’ll be back to Eugene in August and I plan to get right to work.


  2. Oh no! sad bees!

    Your hives are lucky to have such a dedicated beekeeper. I want to have bees so I can have a reason to bust out the microscope. Or maybe I don’t want the bees here to give me a reason to bust out the microscope.

    Do you have any updates on the health of this hive? Do you think one of your other hives might swarm this year so you can replace this one if it doesn’t make it (or pass it along to a novice bee keeping friend)?

    1. The sad news is that, indeed, this hive did not survive the winter. I’m getting a couple more 4 lb. “packages” this year to replace the winter losses. It’s not the way I like to do it, but little choice this year. You never know when a swarm will show up. I’m always ready to catch one.

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